Bipolar surgical instrument

ABSTRACT

A bipolar forceps includes a mechanical forceps including first and second shafts each having a jaw member extending from a distal end thereof and a handle disposed at a proximal end thereof for effecting movement of the jaw members relative to one another about a pivot. A disposable housing is configured to releasably couple to at least one of the shafts and an electrode assembly is configured to releasably couple to the disposable housing. The electrode assembly includes electrodes releasably coupleable to the jaw members. At least one of the electrodes includes a knife channel configured to receive a knife blade there through to cut tissue grasped between the jaw members. An actuation mechanism is configured to selectively advance the knife blade through the knife channel to cut tissue.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a U.S. National Stage Application under 35U.S.C. §371(a) of PCT/CN2013/080953 filed Aug. 7, 2013, the entirecontents of which are incorporated by reference herein.

BACKGROUND

1. Background of Related Art

The present disclosure relates to forceps used for open surgicalprocedures. More particularly, the present disclosure relates to abipolar forceps for treating tissue that is capable of sealing andcutting tissue.

2. Technical Field

A hemostat or forceps is a simple plier-like tool which uses mechanicalaction between its jaws to constrict vessels and is commonly used inopen surgical procedures to grasp, dissect and/or clamp tissue.Electrosurgical forceps utilize both mechanical clamping action andelectrical energy to effect hemostasis by heating the tissue and bloodvessels to coagulate, cauterize and/or seal tissue.

Certain surgical procedures require sealing and cutting blood vessels orvascular tissue. Several journal articles have disclosed methods forsealing small blood vessels using electrosurgery. An article entitledStudies on Coagulation and the Development of an Automatic ComputerizedBipolar Coagulator, J. Neurosurg., Volume 75, Jul. 1991, describes abipolar coagulator which is used to seal small blood vessels. Thearticle states that it is not possible to safely coagulate arteries witha diameter larger than 2 to 2.5 mm. A second article is entitledAutomatically Controlled Bipolar Electrocoagulation—“COA-COMP”,Neurosurg. Rev. (1984), pp. 187-190, describes a method for terminatingelectrosurgical power to the vessel so that charring of the vessel wallscan be avoided.

By utilizing an electrosurgical forceps, a surgeon can either cauterize,coagulate/desiccate, reduce or slow bleeding and/or seal vessels bycontrolling the intensity, frequency and duration of the electrosurgicalenergy applied to the tissue. Generally, the electrical configuration ofelectrosurgical forceps can be categorized in two classifications: 1)monopolar electrosurgical forceps; and 2) bipolar electrosurgicalforceps.

Monopolar forceps utilize one active electrode associated with theclamping end effector and a remote patient return electrode or pad whichis typically attached externally to the patient. When theelectrosurgical energy is applied, the energy travels from the activeelectrode, to the surgical site, through the patient and to the returnelectrode.

Bipolar electrosurgical forceps utilize two generally opposingelectrodes which are disposed on the inner opposing surfaces of the endeffectors and which are both electrically coupled to an electrosurgicalgenerator. Each electrode is charged to a different electric potential.Since tissue is a conductor of electrical energy, when the effectors areutilized to grasp tissue therebetween, the electrical energy can beselectively transferred through the tissue.

SUMMARY

The present disclosure relates to forceps used for open surgicalprocedures. More particularly, the present disclosure relates to abipolar forceps for treating tissue that is capable of sealing andcutting tissue.

As is traditional, the term “distal” refers herein to an end of theapparatus that is farther from an operator, and the term “proximal”refers herein to the end of the electrosurgical forceps that is closerto the operator.

The bipolar forceps includes a mechanical forceps including first andsecond shafts. A jaw member extends from a distal end of each shaft. Ahandle is disposed at a proximal end of each shaft for effectingmovement of the jaw members relative to one another about a pivot from afirst position wherein the jaw members are disposed in spaced relationrelative to one another to a second position wherein the jaw memberscooperate to grasp tissue. A disposable housing is configured toreleasably couple to one or both of the shafts. An electrode assembly isassociated with the disposable housing and has a first electrodereleasably coupleable to the jaw member of the first shaft and a secondelectrode releasably coupleable to the jaw member of the second shaft.Each electrode is adapted to connect to a source of electrosurgicalenergy to allow selective conduction of electrosurgical energy throughtissue. One or both of the electrodes includes a knife channel definedalong its length. The knife channel is configured to receive a knifeblade therethrough to cut tissue grasped between the jaw members. Anactuation mechanism is at least partially disposed within the housingand configured to selectively advance the knife blade through the knifechannel to cut tissue.

Additionally or alternatively, the bipolar forceps may also include aknife lockout mechanism configured to prohibit advancement of the knifeblade into the knife channel when the jaw members are in the firstposition.

Additionally or alternatively, the knife lockout mechanism may move froma first position wherein the knife lockout mechanism engages theactuation mechanism when the jaw members are in the first position to asecond position wherein the knife lockout mechanism disengages theactuation mechanism when the jaw members are in the second position topermit selective advancement of the knife blade through the knifechannel.

Additionally or alternatively, at least one of the shafts may beconfigured to engage the knife lockout mechanism upon movement of thejaw members to the second position and move the knife lockout mechanismout of engagement with the actuation mechanism to permit advancement ofthe knife blade through the knife channel.

Additionally or alternatively, the bipolar forceps may also include atleast one depressible button supported by the housing configured toselectively deliver electrosurgical energy to the electrodes.

Additionally or alternatively, the pivot may define a longitudinal slottherethrough and the knife blade may be configured to move within thelongitudinal slot upon translation thereof.

Additionally or alternatively, the bipolar forceps may also include atleast one handle member extending from the housing. The at least onehandle member may be operably coupled to the actuation mechanism andconfigured to effect advancement of the knife blade through the knifechannel.

Additionally or alternatively, each of the electrodes may include anelectrically conductive sealing surface and an insulating substratecoupled thereto.

Additionally or alternatively, each of the electrodes may include atleast one mechanical interface configured to complement a correspondingmechanical interface on one of the jaw members to releasably couple theelectrode to the jaw member.

Additionally or alternatively, the actuation mechanism may include abiasing member configured to bias the actuation mechanism to anunactuated position.

Additionally or alternatively, the bipolar forceps may also include aknife guide supported in the housing and having a longitudinal slotdefined therethrough that receives the knife blade therein to align theknife blade with the knife channel.

According to another aspect of the present disclosure, a bipolar forcepsis provided. The bipolar forceps includes a mechanical forceps includingfirst and second shafts each having a jaw member extending from itsdistal end. A handle is disposed at a proximal end of each shaft foreffecting movement of the jaw members relative to one another about apivot from a first position wherein the jaw members are disposed inspaced relation relative to one another to a second position wherein thejaw members cooperate to grasp tissue. A disposable housing has opposinghalves configured to releasably couple to each other to at leastpartially encompass one or both of the shafts. An electrode assembly isassociated with the disposable housing and has a first electrodereleasably coupleable to the jaw member of the first shaft and a secondelectrode releasably coupleable to the jaw member of the second shaft.Each electrode is adapted to connect to a source of electrosurgicalenergy to allow selective conduction of electrosurgical energy throughtissue held therebetween. At least one of the electrodes includes aknife channel defined along a length thereof, the knife channelconfigured to receive a knife blade therethrough to cut tissue graspedbetween the jaw members. An actuation mechanism is at least partiallydisposed within the housing and is configured to selectively advance theknife blade through the knife channel to cut tissue. A knife lockoutmechanism is configured to move from a first position wherein the knifelockout mechanism engages the actuation mechanism to prohibitadvancement of the knife blade through the knife channel when the jawmembers are in the first position to a second position wherein the knifelockout mechanism disengages the actuation mechanism when the jawmembers are in the second position to permit advancement of the knifeblade through the knife channel.

Additionally or alternatively, at least one of the shafts may beconfigured to engage the knife lockout mechanism upon movement of thejaw members to the second position and move the knife lockout mechanismout of engagement with the actuation mechanism and permit advancement ofthe knife blade through the knife channel.

Additionally or alternatively, the pivot may define a longitudinal slottherethrough and the knife blade may be configured to advance throughthe longitudinal slot upon translation thereof.

Additionally or alternatively, the bipolar forceps may also include aknife guide supported in the housing and having a longitudinal slotdefined therethrough that receives the knife blade therein to align theknife blade with the knife channel.

Additionally or alternatively, the bipolar forceps may also include atleast one handle member configured to effect advancement of the knifeblade through the knife channel. The at least one handle member mayextend from the housing and may be operably coupled to the actuationmechanism.

According to another aspect of the present disclosure, a bipolar forcepsis provided. The bipolar forceps includes a mechanical forceps includingfirst and second shafts each having a jaw member extending from itsdistal end. A handle is disposed at a proximal end of each shaft foreffecting movement of the jaw members relative to one another about apivot from a first position wherein the jaw members are disposed inspaced relation relative to one another to a second position wherein thejaw members cooperate to grasp tissue therebetween. A disposable housingis configured to be releasably coupled to at least one of the shafts. Anelectrode assembly is configured to releasably couple to the jaw membersand is adapted to connect to a source of electrosurgical energy to allowselective conduction of electrosurgical energy through tissue heldbetween the jaw members. At least one of the jaw members includes aknife channel defined along its length. The knife channel is configuredto receive a knife blade therethrough to cut tissue grasped between thejaw members. A knife guide is supported in the housing and has alongitudinal slot defined therethrough that receives the knife bladetherein to align the knife blade with the knife channel. An actuationmechanism is at least partially disposed within the housing and isconfigured to selectively advance the knife blade through the knifechannel to cut tissue. At least one handle member extends from thehousing. The at least one handle member is operably coupled to theactuation mechanism and is configured to effect advancement of the knifeblade through the knife channel. A knife lockout mechanism is configuredto be engaged by at least one of the shaft members and move the knifelockout mechanism from a first position wherein the knife lockoutmechanism engages the actuation mechanism to prohibit advancement of theknife blade into the knife channel when the jaw members are in the firstposition to a second position wherein the knife lockout mechanismdisengages the actuation mechanism when the jaw members are in thesecond position to permit selective advancement of the knife bladethrough the knife channel.

Additionally or alternatively, the knife guide may extend through alongitudinal slot defined through the pivot.

Additionally or alternatively, the at least one handle member may bemoveable from a first position wherein the knife blade is disposedwithin the housing to a second position wherein the knife blade isadvanced through the knife channel.

Additionally or alternatively, the actuating mechanism may include abiasing member configured to bias the at least one movable handle fromthe second position to the first position.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1 is a perspective view of a bipolar forceps according to anembodiment of the present disclosure including a mechanical forceps, adisposable housing, and a disposable electrode assembly;

FIG. 2 is an enlarged, perspective view of a distal end of the bipolarforceps of FIG. 1;

FIG. 3 is a perspective view of the bipolar forceps of FIG. 1 with partsseparated;

FIG. 4 is an enlarged, internal side view of the disposable housing andthe disposable electrode assembly of FIG. 1 with parts partiallyremoved;

FIG. 5 is a greatly-enlarged, perspective view of the disposableelectrode assembly of FIG. 1;

FIGS. 6 and 7 are greatly-enlarged perspective views of electrodes ofthe disposable electrode assembly of FIG. 1 with parts separated;

FIG. 8 is a perspective view of the bipolar forceps of FIG. 1 graspingtissue to effect a tissue seal; and

FIGS. 9A-9C are generally internal, side views of the bipolar forceps ofFIG. 1 depicting a sequence of motions to illustrate operation of thebipolar forceps.

DETAILED DESCRIPTION

Referring initially to FIGS. 1-3, a bipolar forceps 10 for use with opensurgical procedures includes a mechanical forceps 20 having an endeffector 24 and a disposable electrode assembly 21. Mechanical forceps20 includes first and second elongated shaft members 12 and 14.Elongated shaft member 12 includes proximal and distal end portions 13and 17, respectively, and elongated shaft member 14 includes proximaland distal end portions 15 and 19, respectively. Disposed at proximalend portions 13, 15 of shaft members 12, 14 are handle members 16 and18, respectively, that are configured to allow a user to effect movementof at least one of the shaft members 12 and 14 relative to the other.The end effector 24 includes opposing jaw members 42, 44 that extendfrom the distal end portions 17 and 19 of shaft members 12 and 14,respectively. The jaw members 42, 44 are movable relative to each otherin response to movement of shaft members 12, 14.

Shaft members 12 and 14 are affixed to one another about a pivot 25 suchthat movement of shaft members 12, 14, imparts movement of the jawmembers 42, 44 from a first configuration (FIG. 9A) wherein the jawmembers 44, 42 are disposed in spaced relation relative to one another,e.g., an open configuration, to a second configuration (FIGS. 9B and 9C)wherein the jaw members 42, 44 cooperate to grasp tissue 150therebetween (FIG. 8), e.g., a clamping or closed configuration. In someembodiments, the forceps 10 may be configured such that movement of oneor both of the shaft members 12, 14 causes only one of the jaw membersto move with respect to the other jaw member. Pivot 25 includes a pairof generally semi-circular shaped apertures 25 a, 25 b disposedtherethrough and is configured to be seated in a pivot aperture 29 (FIG.3) such that pivot 25 is permitted to freely rotate within pivotaperture 29, as further detailed below.

Each shaft member 12 and 14 also includes a ratchet portion 32 and 34,respectively. Each ratchet 32, 34 extends from the proximal end portion13, 15 of its respective shaft member 12, 14 towards the other ratchetin a generally vertically aligned manner such that the inner facingsurfaces of each ratchet 32 and 34 abut one another when the shaftmembers 12, 14 are approximated. Each ratchet 32 and 34 includes aplurality of flanges 31 and 33 (FIG. 3), respectively, that project fromthe inner facing surface of each ratchet 32 and 34 such that theratchets 32 and 34 may interlock at one or more positions. In someembodiments, each ratchet position holds a particular strain energy inthe shaft members 12 and 14 to impart a specific closure force to theend effector 24. At least one of the shaft members, e.g., shaft member12, includes a tang 99 that facilitates manipulation of forceps 20during surgical conditions as well as facilitates attachment ofelectrode assembly 21 on mechanical forceps 20 as will be described ingreater detail below.

Referring to FIGS. 2 and 3, disposable electrode assembly 21 isconfigured to releasably couple to mechanical forceps 20, as detailedbelow, and is operably coupled to a housing 70 having a pair of housinghalves 70 a, 70 b configured to matingly engage and releasably encompassat least a portion of shaft member 14. Housing 70 also serves to house aknife 85 having a sharpened distal cutting edge 89 (FIG. 9C), a knifeguide 86 having a longitudinal slot 87 (FIG. 3) configured to receivethe knife blade 85 therein, and a knife actuation mechanism 90 (FIG. 3)configured to effect advancement of the knife blade 85 through a knifechannel 58 (FIG. 2) defined in one or both electrodes 110, 120 totransect tissue, as further detailed below. An interior of each ofhousing half 70 a, 70 b may include a plurality of cooperatingmechanical interfaces disposed at various positions to effect mechanicalcoupling of housing halves 70 a, 70 b to form housing 70.

As shown in FIGS. 4 and 5, a pair of wires 61 and 62 are electricallyconnected to the electrodes 120 and 110, respectively, and are bundledto form a cable 28 that extends through housing 70 and terminates at aterminal connector 30 (FIGS. 1 and 3) configured to mechanically andelectrically couple to a suitable energy source such as anelectrosurgical generator (not shown). One example of an electrosurgicalgenerator is the LIGASURE® Vessel Sealing Generator and the ForceTriad®Generator sold by Covidien. In some embodiments, one or both of handlemembers 16 and 18 may include a suitable mechanical interface (e.g., awire holder) configured to releasably retain cable 28 to aid in keepingcable 28 from interfering with a surgeon's hands during operation offorceps 10.

Referring now to FIGS. 3-7, electrode assembly 21 includes a generallycircular boss member 49 configured to be seated (e.g., friction fit)within a complementary aperture 71 disposed through a distal end ofhousing half 70 a to releasably attach electrode assembly 21 thereto.Electrode assembly 21 is bifurcated such that two prong-like members 103and 105 extend distally therefrom to support electrodes 110 and 120,respectively. Electrode 120 includes an electrically conductive sealingsurface 126 configured to conduct electrosurgical energy therethroughand an electrically insulative substrate 121 that serves to electricallyinsulate jaw member 42 from sealing surface 126. Sealing surface 126 andsubstrate 121 are attached to one another by any suitable method ofassembly such as, for example, snap-fit engagement or by overmoldingsubstrate 121 to sealing surface 126. In some embodiments, substrate 121is made from an injection molded plastic material. Substrate 121includes a plurality of bifurcated anchor members 122 extendingtherefrom that are configured to compress during insertion into acorresponding plurality of sockets 43 disposed at least partiallythrough an inner facing surface 47 (FIG. 3) of jaw member 44 andsubsequently expand to releasably engage corresponding sockets 43 afterinsertion to couple electrode 120 to inner facing surface 47. Substrate121 also includes an alignment pin 124 (FIG. 6) that is configured toengage an aperture 65 disposed at least partially through inner facingsurface 47 of jaw member 44 to ensure proper alignment of electrode 120with jaw member 44 during assembly. Conductive sealing surface 126includes an extension 135 having a wire crimp 117 configured to beinserted into the distal end 106 of prong 105 of electrode assembly 21and electrically connect to wire 61 disposed therein (FIG. 5).

Substantially as described above with respect to electrode 120,electrode 110 includes an electrically conductive sealing surface 116configured to conduct electrosurgical energy therethrough and anelectrically insulative substrate 111 attached thereto, as shown in FIG.7. Substrate 111 includes a plurality of bifurcated anchor members 112extending therefrom that are configured to compress during insertioninto a corresponding plurality of sockets 41 disposed at least partiallythrough an inner facing surface 45 (FIG. 3) of jaw member 42 andsubsequently expand to releasably engage corresponding sockets 41 afterinsertion to couple electrode 110 to inner facing surface 45. Substrate111 also includes an alignment pin 128 (FIG. 4) that is configured toengage an aperture 67 disposed at least partially through inner facingsurface 45 of jaw member 42 to ensure proper alignment of electrode 110with jaw member 42 during assembly. Sealing surface 116 includes anextension 155 having a wire crimp 119 extending therefrom configured tobe inserted into the distal end 104 of prong 103 of electrode assembly21 and electrically connect to wire 62 disposed therein. Substrate 111includes an extension 165 extending proximally therefrom and configuredto couple to extension 155 of sealing surface 116.

Referring to FIG. 4, at least one of the prong members 103, 105 isflexible such that prong members 105 and 103 are readily moveablerelative to each other. In some embodiments, the electrode assembly 21is removably attached to the mechanical forceps 20 by initially movingprongs 103, 105 towards each other. While jaw members 42, 44 are in anopen configuration, the electrodes 120 and 110 may be slid betweenopposing jaw members 44 and 42 such that anchor members 122 and 112 andguide pins 124 and 128, respectively, may be aligned with and releasablyinserted into corresponding sockets 43 and 41 or apertures 65 and 67,respectively, to couple electrodes 120 and 110 with jaw members 44 and42, respectively. Housing halves 70 a, 70 b may then be releasablycoupled to form housing 70 to encompass at least a portion of shaftmember 14 in the manner described above.

To electrically control the end effector 24, the housing 70 supports apair of depressible activation buttons 50 a, 50 b that are operable bythe user to actuate corresponding switches 60 a, 60 b, respectively,disposed within housing 70. Although not explicitly shown, switches 60a, 60 b are electrically interconnected with wires 61, 62, respectively,and serve to initiate and terminate the delivery of electrosurgicalenergy from a suitable energy source to the end effector 24 to effect atissue seal.

Once a tissue seal is established, the knife blade 85 may be advancedthrough the knife channel 58 to transect the sealed tissue, as detailedbelow. However, in some embodiments, knife blade 85 may be advancedthrough the knife channel 58 before, during, or after tissue sealing. Insome embodiments, a knife lockout mechanism 80 is provided to preventextension of the knife blade 85 into the knife channel 58 when the jawmembers 42, 44 are in the open configuration, thus preventing accidentalor premature transection of tissue, as detailed below.

With reference to FIG. 3, the knife actuation mechanism 90 is operablyassociated with a trigger 45 having opposing handle members 45 a, 45 bextending from opposing sides of housing 70. Upon actuation of handlemembers 45 a, 45 b, the knife actuation mechanism 90 responds utilizinga series of inter-cooperating elements to actuate the knife blade 85through the knife channel 58 to sever tissue grasped between jaw members42, 44, as detailed below with reference to FIG. 9C. More specifically,the knife actuation mechanism 90 includes a first link 92 operablycoupled at one end to a shaft member 47 and at an opposing end to asecond link 94 by a pivot pin 92 a. Shaft member 47 extends laterallythrough housing 70 to operably connect handle members 45 a, 45 b fromopposing sides of housing 70. The second link 94 is operably coupled atone end to the first link 92 by the pivot pin 92 a and at the other endto a proximal end of the knife blade 85 by a pivot pin 94 a (FIG. 9A).Shaft member 14 defines a longitudinal slot 14 a therethrough that isconfigured to receive first and second links 92, 94 therein. First andsecond links 92, 94 extend through longitudinal slot 14 a and are freeto move therethrough upon actuation of the handle members 45 a, 45 b, asfurther detailed below with reference to FIG. 9C.

A biasing member 95 (e.g., torsion spring) is disposed coaxially aboutat least a portion of the shaft member 47 between the first link 92 andhandle member 45 a. The biasing member 95 is operably coupled at one endto a portion of the first link 92 and at the other end to a suitablemechanical interface within the housing 70 that braces or stabilizesbiasing member 95 during use of the knife actuation mechanism 90. Thebiasing member 95 serves to bias the trigger 45 such that subsequent toactuation of the knife blade 85 through the knife channel 58 (FIG. 9C),handle members 45 a, 45 are biased to return to an unactuated position(FIGS. 9A and 9B), thereby retracting the knife blade 85 proximally toan unactuated position (FIGS. 9A and 9B).

With reference to FIG. 3, pivot 25 includes a pair of apertures 25 a, 25b disposed therethrough that are configured to receive a pair ofcomplementary raised portions 13 a, 13 b therein, respectively,extending from the distal end portion 17 of shaft member 12 and defininga longitudinal passageway 27 therebetween. Raised portions 13 a, 13 bextend sufficiently from the distal portion of shaft member 14 so thatapertures 25 a, 25 b may receive raised portions 13 a, 13 b therein,respectively, while maintaining pivot 25 in spaced relation with thedistal portion of shaft member 14 to allow the knife guide 86 to bereceived through passageway 27. Movement of shaft members 12, 14relative to each other causes rotational movement of pivot 25 withinpivot aperture 29.

A knife guide 86 is supported within the housing 70 between the endeffector 24 and the knife actuation mechanism 90 and extends throughpassageway 27. The longitudinal slot 87 of the knife guide 86 provideslateral support to the knife blade 85 and constrains side-to-sidelateral motion of the knife blade 85. Thus, the distal knife guide 86serves to urge the knife blade 85 into a central position relative toend effector 24, thereby ensuring proper alignment of the knife blade 85as the knife blade 85 enters the knife channel 58 (FIG. 2) defined inelectrodes 110, 120.

In some embodiments, the forceps 10 includes a knife blade lockoutmechanism 80 supported within the housing 70 and that serves to preventadvancement of the knife blade 85 into the knife channel 85 when the jawmembers 42, 44 are in the open configuration (FIG. 9A). With referenceto FIG. 3, the knife blade lockout mechanism 80 includes a safety link81 operably coupled with a biasing member 83 (e.g., a leaf spring) andpivotally supported within the housing 70. In the open configuration ofjaw members 42, 44, the knife blade 85 is in an unactuated position(FIG. 9A and 9B) and the safety link 81 is engaged with pivot pin 94 a(FIG. 9A) such that distal advancement of knife blade 85 is prohibited.As shown in FIG. 1, housing 70 includes a longitudinal opening 70 c thatopposes shaft member 12 and exposes the knife blade lockout mechanism 80such that upon approximation of the shaft members 12, 14 to move the jawmembers 42, 44 to the closed position (FIG. 9B), safety link 81 isengaged by shaft member 12. Pressure applied to safety link 81 byapproximation of shaft members 12, 14 operates to bias the biasingmember 83 against the knife blade 85 and, in turn, rotate the safetylink 81 out of engagement with the pivot pin 94 a (FIG. 9B) such thatknife blade 85 is permitted to advance distally into the knife channel58 (FIG. 9C). Operation of the knife actuation mechanism 90, the knifelockout mechanism 80, and actuation of the knife blade 85 is furtherdetailed below with reference to FIGS. 9A-9C.

The tissue seal thickness and tissue seal effectiveness may beinfluenced by the pressure applied to tissue between jaw members 44, 42and the gap distance between the opposing electrodes 110 and 120 (FIG.5) during tissue sealing. In the closed configuration, a separation orgap distance “G” may be maintained between the sealing surfaces 116, 126by an array of stop members 54 (FIG. 2) disposed on one or both ofsealing surfaces 116, 126 (only shown disposed on sealing surface 126for purposes of illustration). The stop members 54 contact the sealingsurface on the opposing jaw member and prohibit further approximation ofthe sealing surfaces 116, 126. In some embodiments, to provide aneffective tissue seal, an appropriate gap distance of about 0.001 inchesto about 0.010 inches and, desirably, between about 0.002 and about0.005 inches may be provided. In some embodiments, the stop members 54are constructed of an electrically non-conductive plastic or othermaterial molded onto the sealing surfaces 116, 126, e.g., by a processsuch as overmolding or injection molding. In other embodiments, the stopmembers 54 are constructed of a heat-resistant ceramic deposited ontosealing surfaces 116, 126.

FIG. 8 shows the bipolar forceps 10 during use wherein the shaft members12 and 14 are approximated to apply clamping force to tissue 150 and toeffect a tissue seal. Once sealed, tissue 150 may be cut along thetissue seal through actuation of the knife blade 85, as detailed belowwith reference to FIGS. 9A-9C.

In some embodiments, the performance of forceps 10 may be tested using avirtual tissue vessel. More specifically, the user may place a virtualtissue vessel between sealing surfaces 116, 126 and apply a clampingforce to the vessel. The virtual tissue vessel may be, for example, anysuitable plastic having impedance. The user may seal the virtual tissuevessel using electrosurgical energy from a suitable electrosurgicalgenerator, e.g., LIGASURE® Vessel Sealing Generator and the ForceTriad®Generator sold by Covidien. The user may also actuate the handle members45 a, 45 b to advance the knife blade 85 through the knife channel 58 tocut the sealed virtual tissue vessel. In this scenario, theelectrosurgical generator may be configured to automatically run a testprocedure that serves to sense the applied clamping force, the gapdistance between the opposing electrodes 110, 120, and/or the impedanceof the virtual tissue vessel before, during, or after sealing. From thissensed information, the electrosurgical generator may serve to verifythat the forceps 10 is in proper working condition (e.g., properclamping force, gap distance, etc.) following assembly of the electrodeassembly 21 to the mechanical forceps 20 and prior to use of theassembled forceps 10 in a vessel sealing procedure.

Referring now to FIGS. 9A, 9B, and 9C, a sequence of motions may beinitiated by moving the shaft members 12, 14 in order to close the jawmembers 42, 44, and by rotating the handle members 45 a, 45 b to inducethe knife actuation mechanism 90 to translate the knife blade 85 throughthe knife channel 58. Initially, shaft members 12, 14 are in the openconfiguration and the handle members 45 a, 45 b are in an un-actuatedposition as depicted in FIG. 9A. This arrangement of shaft members 12,14 and handle members 45 a, 45 b sustains the end effector 24 in theopen configuration wherein the jaw members 42, 44 are substantiallyspaced from one another, and the knife blade 85 is in a retracted orproximal position with respect to the jaw members 42, 44. The initialposition of the handle members 45 a, 45 b depicted in FIGS. 9A and 9B isactively maintained by the influence of the biasing member 95 on thetrigger 45. When jaw members 42, 44 are in the open configuration, asdepicted in FIG. 9A, safety link 81 is engaged with pivot pin 94 a suchthat rotational motion of the handle members 45 a, 45 b in a proximaldirection (depicted by rotational arrow A4 in FIG. 9C) is prohibited sothat knife blade 85 is prohibited from advancing into knife channel 58.

The jaw members 42, 44 may be moved from the open configuration of FIG.9A to the closed configuration depicted in FIG. 9B. As the shaft members12, 14 pivot about pivot 25 in the directions of arrows A1 and A2 (FIG.9B), respectively, shaft member 12 engages safety link 81. As the shaftmembers 12, 14 pivot further about pivot 25 in the directions of arrowsA1 and A2, respectively, shaft member 12 applies a force on the safetylink 81 that causes biasing member 83 to flex against the bias of knifeblade 85, thereby inducing rotation of the safety link 81 in thedirection depicted by rotational arrow A3 in FIG. 9B. Rotation of safetylink 81 in the direction of rotational arrow A3 operates to move thesafety link 81 out of engagement with pivot pin 94 a as shown in FIG.9C.

Upon movement of the safety link 81 out of engagement with the pivot pin94 a, handle members 45 a, 45 b may be selectively moved from theunactuated configuration of FIGS. 9A and 9B to the actuated position ofFIG. 9C to advance the knife blade 85 distally through knife channel 58.More specifically, as handle members 45 a, 45 b rotate in the generalproximal direction, depicted by rotational arrow A4, to the actuatedconfiguration depicted in FIG. 9C, the first link 92 imparts arotational force on second link 94, thereby causing second link 94 torotate about pivot pin 94 a and move in a general distal direction toadvance knife blade 85 distally into the knife channel 58.

In some embodiments, the knife actuation mechanism 90 may be positionedrelative to shaft member 14 different than the depiction of knifeactuation mechanism 90 in FIG. 3. For example, if the knife actuationmechanism 90 depicted in FIG. 3 is disposed substantially between shaftmembers 14 and 12, then in some embodiments, knife actuation mechanism90 may be disposed on an opposing side of shaft member 14 such thatshaft member 14 is disposed between knife actuation mechanism 90 andshaft member 12. In this scenario, shaft members 12, 14 may bealternatively configured to allow knife blade 85 to advance throughlongitudinal passageway 27 defined by raised portions 13 a, 13 b (e.g.,via knife guide 86) and into knife channel 58. For example, the distalends 17, 19 of shaft members 12, 14, respectively, may be configured invarious interlocking relationships (e.g., a lock-box configuration) thatfacilitate the knife 85 entering the knife channel 58 in variousorientations relative to shaft members 12, 14 and/or knife channel 58.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely as examplesof particular embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

Although the foregoing disclosure has been described in some detail byway of illustration and example, for purposes of clarity orunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims.

What is claimed is:
 1. A bipolar forceps, comprising: a mechanicalforceps including first and second shafts each having a jaw memberextending from a distal end thereof and a handle disposed at a proximalend thereof for effecting movement of the jaw members relative to oneanother about a pivot from a first position wherein the jaw members aredisposed in spaced relation relative to one another to a second positionwherein the jaw members cooperate to grasp tissue therebetween; adisposable housing configured to releasably couple to at least one ofthe shafts; an electrode assembly associated with the disposable housingand having a first electrode releasably coupleable to the jaw member ofthe first shaft and a second electrode releasably coupleable to the jawmember of the second shaft, each electrode adapted to connect to asource of electrosurgical energy to allow selective conduction ofelectrosurgical energy through tissue held therebetween; at least one ofthe electrodes including a knife channel defined along a length thereof,the knife channel configured to receive a knife blade therethrough tocut tissue grasped between the jaw members; and an actuation mechanismat least partially disposed within the housing and configured toselectively advance the knife blade through the knife channel to cuttissue.
 2. The bipolar forceps according to claim 1, further comprisinga knife lockout mechanism configured to prohibit advancement of theknife blade into the knife channel when the jaw members are in the firstposition.
 3. The bipolar forceps according to claim 2, wherein the knifelockout mechanism moves from a first position wherein the knife lockoutmechanism engages the actuation mechanism when the jaw members are inthe first position to a second position wherein the knife lockoutmechanism disengages the actuation mechanism when the jaw members are inthe second position to permit selective advancement of the knife bladethrough the knife channel.
 4. The bipolar forceps according to claim 2,wherein at least one of the shafts is configured to engage the knifelockout mechanism upon movement of the jaw members to the secondposition and move the knife lockout mechanism out of engagement with theactuation mechanism to permit advancement of the knife blade through theknife channel.
 5. The bipolar forceps according to claim 1, furthercomprising at least one depressible button supported by the housingconfigured to selectively deliver electrosurgical energy to theelectrodes.
 6. The bipolar forceps according to claim 1, wherein thepivot defines a longitudinal slot therethrough and the knife blade isconfigured to move within the longitudinal slot upon translationthereof.
 7. The bipolar forceps according to claim 1, further comprisingat least one handle member configured to effect advancement of the knifeblade through the knife channel, the at least one handle memberextending from the housing and operably coupled to the actuationmechanism.
 8. The bipolar forceps according to claim 1, wherein each ofthe electrodes includes an electrically conductive sealing surface andan insulating substrate coupled thereto.
 9. The bipolar forcepsaccording to claim 1, wherein each of the electrodes includes at leastone mechanical interface configured to complement a correspondingmechanical interface on one of the jaw members to releasably couple theelectrode to the jaw member.
 10. The bipolar forceps according to claim1, wherein the actuation mechanism includes a biasing member configuredto bias the actuation mechanism to an unactuated position.
 11. Thebipolar forceps according to claim 1, further comprising a knife guidesupported in the housing and having a longitudinal slot definedtherethrough that receives the knife blade therein to align the knifeblade with the knife channel.
 12. A bipolar forceps, comprising: amechanical forceps including first and second shafts each having a jawmember extending from a distal end thereof and a handle disposed at aproximal end thereof for effecting movement of the jaw members relativeto one another about a pivot from a first position wherein the jawmembers are disposed in spaced relation relative to one another to asecond position wherein the jaw members cooperate to grasp tissuetherebetween; a disposable housing having opposing halves configured tobe releasably coupled to each other to at least partially encompass atleast one of the shafts; an electrode assembly associated with thedisposable housing and having a first electrode releasably coupleable tothe jaw member of the first shaft and a second electrode releasablycoupleable to the jaw member of the second shaft, each electrode adaptedto connect to a source of electrosurgical energy to allow selectiveconduction of electrosurgical energy through tissue held therebetween;at least one of the electrodes including a knife channel defined along alength thereof, the knife channel configured to receive a knife bladetherethrough to cut tissue grasped between the jaw members; an actuationmechanism at least partially disposed within the housing and configuredto selectively advance the knife blade through the knife channel to cuttissue; and a knife lockout mechanism configured to move from a firstposition wherein the knife lockout mechanism engages the actuationmechanism to prohibit advancement of the knife blade through the knifechannel when the jaw members are in the first position to a secondposition wherein the knife lockout mechanism disengages the actuationmechanism when the jaw members are in the second position to permitadvancement of the knife blade through the knife channel.
 13. Thebipolar forceps according to claim 12, wherein at least one of theshafts is configured to engage the knife lockout mechanism upon movementof the jaw members to the second position and move the knife lockoutmechanism out of engagement with the actuation mechanism to permitadvancement of the knife blade through the knife channel.
 14. Thebipolar forceps according to claim 12, wherein the pivot defines alongitudinal slot therethrough and the knife blade is configured toadvance through the longitudinal slot upon translation thereof.
 15. Thebipolar forceps according to claim 12, further comprising a knife guidesupported in the housing and having a longitudinal slot definedtherethrough that receives the knife blade therein to align the knifeblade with the knife channel.
 16. The bipolar forceps according to claim12, further comprising at least one handle member configured to effectadvancement of the knife blade through the knife channel, the at leastone handle member extending from the housing and operably coupled to theactuation mechanism.
 17. A bipolar forceps, comprising: a mechanicalforceps including first and second shafts each having a jaw memberextending from a distal end thereof and a handle disposed at a proximalend thereof for effecting movement of the jaw members relative to oneanother about a pivot from a first position wherein the jaw members aredisposed in spaced relation relative to one another to a second positionwherein the jaw members cooperate to grasp tissue therebetween; adisposable housing configured to releasably couple to at least one ofthe shafts; an electrode assembly configured to releasably couple to thejaw members and adapted to connect to a source of electrosurgical energyto allow selective conduction of electrosurgical energy through tissueheld between the jaw members; at least one of the jaw members includinga knife channel defined along a length thereof, the knife channelconfigured to receive a knife blade therethrough to cut tissue graspedbetween the jaw members; a knife guide supported in the housing andhaving a longitudinal slot defined therethrough that receives the knifeblade therein to align the knife blade with the knife channel; anactuation mechanism at least partially disposed within the housing andconfigured to selectively advance the knife blade through the knifechannel to cut tissue; at least one handle member extending from thehousing, the at least one handle member operably coupled to theactuation mechanism and configured to effect advancement of the knifeblade through the knife channel; and a knife lockout mechanismconfigured to be engaged by at least one of the shaft members and movethe knife lockout mechanism from a first position wherein the knifelockout mechanism engages the actuation mechanism to prohibitadvancement of the knife blade into the knife channel when the jawmembers are in the first position to a second position wherein the knifelockout mechanism disengages the actuation mechanism when the jawmembers are in the second position to permit selective advancement ofthe knife blade through the knife channel.
 18. The bipolar forcepsaccording to claim 17, wherein the knife guide extends through alongitudinal slot defined through the pivot.
 19. The bipolar forcepsaccording to claim 17, wherein the at least one handle member ismoveable from a first position wherein the knife blade is disposedwithin the housing to a second position wherein the knife blade isadvanced through the knife channel.
 20. The bipolar forceps according toclaim 19, wherein the actuating mechanism includes a biasing memberconfigured to bias the at least one movable handle from the secondposition to the first position.